Background Muscular function, such as handgrip strength, has been suggested as an associated factor for cognitive impairment. This study investigated the association between temporal change in handgrip strength and cognitive function using longitudinal, nationwide data from Korean older adults. Methods Our study used data from the Korean Longitudinal Study of Aging (KLoSA). The analysis covered 6696 participants who had taken the handgrip strength test and Mini-Mental State Examination (MMSE) from 2006 to 2018. We adopted general estimating equations to assess the temporal effect of handgrip strength change on cognitive function. Results After adjusting for covariates, we observed an association between handgrip strength and low MMSE scores (β = − 0.3142 in men, β = − 0.2685 in women). Handgrip strength as a continuous variable was positively correlated with MMSE scores after adjustment (β = 0.0293 in men, β = 0.0347 in women). The group with decreased handgrip strength over time also showed greater odds for mild cognitive impairment (OR = 1.23, 95%CI = 1.05–1.27 in men, OR = 1.15, 95%CI = 1.05–1.27 in women) and dementia (OR = 1.393, 95%CI = 1.18–1.65 in men, OR = 1.19, 95%CI = 1.08–1.32 in women). Conclusions This study identified the relationship between handgrip strength change and cognitive function among South Korean adults. According to our large, longitudinal sample, decreasing handgrip strength was associated with decline in cognitive function.

Background/Aim: Idiopathic pulmonary fibrosis (PF) is a fatal disorder of unknown aetiology with limited treatment options. Chitosan has antibacterial, antifungal, antioxidant, antitumour, and anti-inflammatory effects. This study aimed to investigate the effects of chitosan administration on bleomycin (BLM)-induced PF in rats. Materials and Methods: A PF rat model was established by endotracheal instillation of 5 mg/kg BLM; then, chitosan was administered in drinking water for 3 weeks. Histology, cell counts, and cytokine responses in the bronchoalveolar lavage fluid (BALF) and weight measurements (body and lung) were analyzed to assess its therapeutic effects. Results: Chitosan administration tended to reduce transforming growth factor (TGF)-β1 and interferon (IFN)-γ levels in BALF, and histopathological examination confirmed that chitosan attenuated the degree of inflammation and fibrosis in the lung. Conclusion: This study revealed that oral chitosan exhibits potential antifibrotic effects, as measured by decreased proinflammatory cytokine levels and histological evaluation, in a BLM-induced PF rat model.

In this cohort study, we assessed the association between depression and the risk of Alzheimer’s disease from data obtained from the 2002 to 2013 Korean National Health Insurance Service-Elderly Cohort Database, which accounts for 10% of the South Korean population aged > 60 years. A total 518,466 patients were included in the analysis and followed up, unless they were excluded due to death or migration. Patients who sought treatment for depression or dementia within 1 year of the washout period and who were diagnosed with dementia within the 1-year period of the diagnosis of depression were excluded from the study. The risk of dementia was analysed using Cox proportional hazards models. Patients with a history of depression during the follow-up period were at a higher risk of Alzheimer’s disease than those without a history of depression (HR 3.35, CI 3.27–3.42). The severe-depression group exhibited the highest risk of Alzheimer’s disease (HR 4.41, CI 4.04–4.81), while the mild-depression group exhibited a relatively lower risk of Alzheimer’s disease (HR 3.31, CI 3.16–3.47). The risk of Alzheimer’s disease was associated with depression history and an increased severity of depression increased the risk of Alzheimer’s disease.

Exercise has been considered as treatment and a preventive modality to alleviate depressive symptoms, but sex differences regarding specific types of exercise in association with depression have not been clearly elucidated. Here, we investigated sex differences in the association between exercise type and depression in Korean adults. Data from the Korea National Health and Nutrition Examination Survey (KNHANES) were used for this study. A total of 13,914 participants who had filled in a Patient Health Questionnaire-9 (PHQ-9) were included. The subjects’ exercise status had been evaluated with questions on strength exercise and walking, and answers were analysed in the current study using multivariate logistic regression. Male participants who reported having done strength exercise more than once in a week were less likely to be depressed after adjusting for covariates assumed to affect depression levels [adjusted odds ratio (OR) 0.60, 95% CI 0.40–0.92]. In women, walking more than once during the previous week was associated with lower depression levels after covariate adjustments (adjusted OR 0.54, CI 0.34–0.87). This study identifies the relationship between exercise and the presence of depressive symptoms and finds sex differences in the types of exercise that correlate with depression in Korean adults.

Adolescent depression and suicide have become leading public health and socioeconomic problems. Determining the connection between adolescent behavior and depression can inform strategies to reduce the prevalence of depression and suicide. We investigated the association between sexual behavior and depression in South Korean adolescents. Data for this cross-sectional study were obtained from the 2017–2019 Korea Youth Risk Behavior Web-Based Survey. Data of 178,664 subjects were analyzed using chi-square tests and multivariate logistic regression. After adjusting for covariates, the prevalence of depression was found to be higher in subjects with experience of sexual intercourse (adjusted odds ratio = 1.71, 95% confidence interval = 1.59–1.83 in boys; adjusted odds ratio = 1.47, confidence interval = 1.33–1.61 in girls). On categorizing subjects into two groups based on suicidality, subjects with sexual intercourse experience had higher odds ratios for depression with suicidality (aOR:2.16 in boys, aOR:1.80in girls) than depression without suicidality (aOR:1.49 in boys, aOR:1.25 in girls). We identified the relationship between sexual behavior and the prevalence of depression; adolescents with experience of sexual intercourse were more likely to have depression with suicidality. Further research using prospective designs should serve as the basis for appropriate sex education policies to manage the relationship between sexual behavior and depression.

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Summary Optical clearing has emerged as a powerful tool for volume imaging. Although volume imaging with immunostaining have been successful in many protocols, yet obtaining homogeneously stained thick samples remains challenging. Here, we propose a method for label-free imaging of brain slices by enhancing the regional heterogeneity of the optical properties using the tissue clearing principle. We used FxClear, a method for delipidation of brain tissue, to retain a larger proportion of lipids at the white matter (WM). Furthermore, the embedding media affected the contrasts for the lipid-rich or extracellular matrix-rich areas, depending on their chemical properties. Thus, we tailored clearing conditions for the enhancement of the refractive indices (RIs) differences between gray and WM, or several pathological features. RI differences can be imaged using conventional light microscopy or optical coherence tomography. We propose that our protocol is simple, reliable, and flexible for label-free imaging, easily implementable to routine histology laboratory.